This invention relates to a vehicle navigation system, and more particularly, to a vehicle navigation system that calculates an optimum route to a destination point.
Such a navigation system has two main and interrelated functions: the first function is to display to the user a map of the present vehicle location; and the second function is to provide guidance on a guided route from a starting point to a destination point. The second function is generally referred to as route guidance or selection. A route is typically optimized for one of various parameters, for instance, minimum travel time, minimum travel distance, maximum use of freeway, or other parameters pertaining to movement of a vehicle on a road network.
It is often the case, however, that an optimum route calculated by the system is not necessarily the most preferable route to the driver. We know that it will be most time-efficient to use highways when going from one point to another. Some drivers, nonetheless, prefer to detour at the expense of their time for purely personal reasons. For instance, some drivers prefer to drive narrow winding roads along seacoasts, rather than driving straight highways. Some drivers detour to visit an intermediate location, such as a store, or to enjoy watching scenery of their favorite spots. In calculating an optimum route, conventional navigation systems are ignorant about the driver's personal preference on roads. As a result, those conventional systems try to guide the driver repeatedly along the same calculated optimum route even in cases where the driver's driving history clearly shows that the driver has never followed the optimum route and takes the same detour every time the optimum route is presented.